1. Field of the Invention
The present invention relates to a hydraulic puncher for punching a hole or holes in a workpiece such as a C channel shaped steel member.
2. Description of the Related Art
The conventional hydraulic puncher includes a puncher body having a ram shaft at its lower end, a frame formed under the puncher body, a die holder provided on the lower end of the frame, a single die provided on the die holder and an opening defined between the lower end of the puncher body and the lower end of the frame. After a workpiece has been loaded on the die on the die holder from a lateral side of the hydraulic puncher through the opening, a hole or holes are formed in the workpiece by means of a punch provided on the ram shaft.
The conventional hydraulic puncher has only a single punch provided on the ram shaft and a die holder which can only mount a single die and has no paired punchers and paired dies. Naturally, the conventional hydraulic puncher has no paired punches or paired dies which can be rotated through 90.degree..
When a row or rows of holes are punch-formed in an elongated workpiece, therefore, it must be moved lengthwise on the die every time a hole is formed. Thus, it takes a long time for the conventional hydraulic puncher to form the holes in such a long workpiece.
Further, it is difficult to form a hole or holes accurately and easily in an end portion of an elongated workpiece, because the die holder cannot be rotated through 90.degree. about its own axis and thus the end of the workpiece cannot be abutted against a workpiece guide member for guiding a lateral side of the workpiece. In either case, the conventional hydraulic puncher is insufficient, leading to poor productivity. Thus, the improvement of the hydraulic puncher has been demanded in this respect.